Loading Coils; was : Vincent antenna
 

I hate to see Cecil and others criticizing Tom's (W8JI) measurements,
although I've certainly learned to expect this sort of response whenever
his theory is shown to be lacking. Tom does a careful job of making
measurements and he has good equipment. Most importantly, he's honest.
If someone finds an error with this measurement methodology or results,
he'll be the first one to correct it. But "finding an error" doesn't
mean just saying that his measurements fail to support a wild theory. It
means making careful measurements with good equipment and methodology
which give different results. I'm sure we'll never see this from Cecil.

Like I did some time ago, Tom has taken the time and trouble to make
measurements which simply confirm what established theory tell us. Then
Cecil and others respond by stating they're in error but haven't
presented any evidence to the contrary. (Sorry, hot air doesn't count as
evidence.) Any readers not astute enough to see the problem here
probably feel at home with astrology, homeopathy, and other alternative
disciplines that elicit belief without evidence.

Roy Lewallen, W7EL

Jim Lux wrote:
John Smith wrote:
Cecil Moore wrote:

AI4QJ wrote:

That is his "obvious" explanation. He should remove that from his
webpage as it is rather embarassing.


W8JI made a gross error in his measurement and
then tried to rationalize the impossible result.


Cecil:

How would you have like to be working at NASA, with this group; And,
you were the one responsible for not coverting kilometers to miles and
SMACKING that spacecraft we lost into Mars? ;-)


It wasn't km and miles, it was pounds and newtons AND
the error was that Lockheed Martin supplied the thrust data in pounds,
unlike the contractual requirement to supply it in Newtons (which is
what we at JPL have used for decades). The error wasn't caught because
the absolute magnitude of the force is very small, so the differences
from predict to observation were on the order of the measurement
uncertainty. (We're talking measuring the velocity to mm/sec and range
to mm, when its at Mars.)
I'd venture that anyone would find measuring distances to 1 part in 1E12
challenging...





Crud, I've volunteered on serving on those soup-lines, would hate to
have seen ya' there. chuckle

Regards,
JS

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Tom Donaly wrote:
Do you really believe that an antenna + loading coil has
to be a quarter wave long to resonate?

Note: I am NOT talking about *physical* lengths.
The phase shift from feedpoint to tip has to be
*electrically 90 degrees* so the answer is yes.
For a base-loaded mobile antenna, the sum of the
phase shifts a

PS1. The phase shift through the loading coil.
PS2. The phase shift at the coil to stinger junction.
PS3. The phase shift in the stinger.

PS1 + PS2 + PS3 = 90 degrees.

In a typical 75m base-loaded mobile antenna, PS1
may be about 40 degrees, PS2 about 40 degrees, and
PS3 about 10 degrees.

PS2 is a freebie lossless phase shift compliments of
Mother Nature caused by the impedance discontinuity
between the coil and the stinger. If that phase shift
can be maximized, it should add to antenna efficiency.

So, since the phase shift has to be 90 degrees, the antenna
should always resonate at the same frequencies a quarter wave
stub of the same electrical length would resonate at, right?
73,
Tom Donaly, KA6RUH

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Tom Donaly wrote:
Your problem is
that you've become so enamored of your little reflection theory that
you insist that only a set of transmission lines 90 degrees in total
length can resonate. Too bad your education isn't complete or you'd know
this isn't so.

Obviously, I am not talking about *physical* length.
The "90 degrees" is the total *electrical* length.
Please tell us how you get resonance out of a stub
that is *electrically* 45 degrees long? No resistive
or reactive components are allowed. Here's your
chance to nail me to the wall.

And, if the total electrical length isn't 90 degrees, you
add a few degrees to the loading coil to make it come out right.
Very ingenious.
73,
Tom Donaly, KA6RUH

Loading Coils; was : Vincent antenna
 

On 29 Nov, 14:52, "Tom Donaly" wrote:
Cecil Moore wrote:
Tom Donaly wrote:
Your problem is
that you've become so enamored of your little reflection theory that
you insist that only a set of transmission lines 90 degrees in total
length can resonate. Too bad your education isn't complete or you'd know
this isn't so.

Obviously, I am not talking about *physical* length.
The "90 degrees" is the total *electrical* length.
Please tell us how you get resonance out of a stub
that is *electrically* 45 degrees long? No resistive
or reactive components are allowed. Here's your
chance to nail me to the wall.

And, if the total electrical length isn't 90 degrees, you
add a few degrees to the loading coil to make it come out right.
Very ingenious.
73,
Tom Donaly, KA6RUH

I feel that many are disregarding the basics with respect to antennas!
It is one thing to say that an antenna is resonant which amateurs
are interested in for matching purposes. This is totally different
from being resonant AND in equilibrium which is demanded by Maxwell,
Newton and others when in the pursuit of the sciences
Art Unwin KB9MZ....xg

Loading Coils; was : Vincent antenna
 

Jim Lux wrote:
While the model is certainly valid within
their stated limitations, the real question that arises is "why".

Because some people are claiming a 3 nS delay through
a 75m mobile loading coil. Corum's VF estimate says
it is more like 40 degrees rather than 4.5 degrees.

Furthermore, people HAVE made current measurements at the top and bottom
of a large tesla coil and found very small phase differences, indicating
that there is little or no deviation from a lumped model.

There is virtually no phase difference in standing-wave
current which is what was being measured. Standing-wave
current cannot be used to measure the delay through a
loading coil.

If the loading coil is located in a traveling-wave
environment, the delay through the coil is obvious
by the phase shift through the coil.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
Cecil Moore wrote:
The referenced W8JI 3 nS "measurement" was the delay
in a 2' dia, 100 T, 10" long loading coil on 4 MHz,
i.e. 4.5 degrees.

Jim's point is that it can be done!

In that particular coil at 4 MHz - no, it cannot be done.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

"Cecil Moore" wrote
All of the boundary test conditions given in Corum's
IEEE white paper are satisfied by a 75m bugcatcher
loading coil. There is no reason to believe that
the underlying principles of physics do not apply.
In fact, the diagram of the 1/4WL resonant system
looks exactly like a base loading coil, stinger,
and top hat as is used for 75m mobile operation.
_____________

Cecil,

Do you believe that a 75m mobile antenna system using an artificially
resonant (as in bugcatcher-loaded), electrically short whip produces the
same elevation pattern and groundwave field strength at 1 km as an unloaded
1/4-wave vertical monopole for 75m with the same applied power using a good,
buried radial r-f ground (say, 2 ohms or less)?

RF

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
It appears you missed the primary message of the Corum article.

I'm afraid you missed the point. As long as the frequency
is kept constant, the VF and Z0 of coil stock will be
relatively constant - why wouldn't it be? W8JI missed
the 4 MHz delay through that coil by at least a magnitude.
It is impossible for that delay to be 3 nS. The measured
delay through my 75m bugcatcher coil is 25 nS.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Roy Lewallen wrote:
I see Cecil is still using misdirection, that old but reliable trick of
illusionists, to try and divert attention away from the flaws in his
imaginative theories.

This ad hominem attack brought to you by the person who
has asserted that he used a current with unchanging phase
to measure the phase shift through a loading coil and
that he stands by that measurement.

Even he will tire of it after a
while, and get back to his waves of average power that bounce off each
other when they collide.

Posting a statement that you know is false is not
ethical. EM waves do have energy which averaged over
a number of cycles is called irradiance in optics.
That energy passing a fixed measurement point is the
average power. And the waves don't bounce off each
other - they superpose, sometimes interfere, and
sometimes cancel.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Jim Kelley wrote:

Cecil Moore wrote:
It is only closed minds that
are the problem now.

A perspective which apparently shifts depending on which side of the
room you happen to be standing.

My mind is open, Jim, but since you refuse to enter into
a technical discussion, I am not likely to change mine.
--
73, Cecil http://www.w5dxp.com